Apparatus for tilting away a part of a signature to be separated from a rack

ABSTRACT

An apparatus for tilting away a part of a sheet to be separated, in which apparatus a compressed-air supply is sufficient for operating the tilting sucker. To this end, the tilting sucker of the apparatus is assigned a vacuum generator which can be fed with compressed air and which generates a vacuum from the supplied compressed air.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to an apparatus for tilting away a part of asignature to be separated from a stack, having at least one sucker whichis arranged on a carrier and can be moved, preferably pivoted, by thecarrier for tilting away a part of the signature to be separated, andhaving at least one supply channel in the carrier for supplying therespective sucker with vacuum.

2. Prior Art

In the print further processing of signatures such as individual sheets,covers or quires, individual signatures are to be pulled off from astack of signatures. In the separation of the signatures which occurs inthis way, first of all a part of the signature to be separated, inparticular an edge strip or a corner region, is tilted away with respectto the stack. An apparatus of the type which is addressed here servesfor this purpose, which apparatus is also known briefly as a tiltingsucker in the specialist language.

An apparatus (tilting sucker) of this type is known which has a suckerwhich is held on a preferably pivotable carrier. The sucker can beloaded with vacuum via a supply line. The known apparatus requires anadditional vacuum supply having a vacuum source. While compressed air isavailable everywhere, vacuum is not always present. Therefore, in orderto operate the known apparatus, a vacuum supply having a vacuumgenerator has to be provided. Moreover, supply lines for compressed airand for vacuum have to be laid to the respective apparatus. Finally,suckers which are fed from a vacuum source are relatively loud.

BRIEF SUMMARY OF THE INVENTION

The invention is based on the object of providing an apparatus fortilting away a corner or a strip of a signature to be separated, itbeing possible to load the sucker of the said apparatus with a vacuum ina simple manner.

An apparatus (tilting sucker) for achieving the abovementioned objecthas the features of an apparatus for tilting away a part of a signatureto be separated from a stack, having at least one sucker which isarranged on a carrier and can be moved, preferably pivoted, by thecarrier for tilting away a part of the signature to be separated, andhaving at least one supply channel in the carrier for supplying therespective sucker with vacuum, characterized in that the carrier isassigned at least one vacuum generator for providing the vacuum which isrequired by the respective sucker. As a result of the fact that thecarrier is assigned at least one vacuum generator for the or eachsucker, the required vacuum is generated, as it were, “in situ”. Thecarrier requires no vacuum supply and also no connection for the latter.

According to one preferred refinement of the invention, the at least onevacuum generator is configured in such a way that it generates a vacuum,that is to say a negative pressure, by using compressed air. The vacuumcan therefore be formed by compressed air which is present in any caseand is required in order to supply compressed air to other parts of theapparatus or to the machine which has the latter, for print furtherprocessing, for example to a collating machine, an adhesive binder or acover feeder.

According to one development of the invention, there is provision forthe or each vacuum generator to be supplied with compressed air, theamount and/or the pressure of which can be changed. In this way, theintensity of the vacuum can be changed. The vacuum which is present atthe sucker can therefore be adapted to the requirements by beingincreased or reduced. The negative pressure at the sucker can be changedin a simple manner by a change in the compressed-air supply of the atleast one vacuum generator by means of an adjusting throttle in thecompressed-air supply line which leads to the vacuum generator or aplurality of valves which can be actuated individually in thecompressed-air supply line. The compressed-air supply to the at leastone vacuum generator can be changed in stages by opening all or onlycertain valves. The valves preferably have different cross sections forthe passage of compressed air. Precisely graduated amounts of compressedair for supplying the or each vacuum generator can be set individuallyby targeted opening of a defined valve or a plurality of defined valves.

The vacuum generator is preferably provided on or in the carrier. Thevacuum generator, that is to say the location, at which the vacuum isgenerated, is situated as a result in the vicinity of the sucker, atwhich the vacuum is required. In this way, the invention permits theshortest possible supply lines between the vacuum generator and thesucker. Only a relatively small amount therefore has to be evacuated, inorder to generate a vacuum at the sucker. In known apparatuses of thistype, the relatively long supply lines have a large internal volumewhich requires a great amount of air to be sucked away, until the longsupply line is evacuated and a vacuum is available at the sucker. Thishas the consequence of high energy consumption and is alsonoise-intensive.

Furthermore, there is provision to supply a supply channel for feedingthe or each sucker with vacuum from the vacuum generator which isassigned to the carrier. The vacuum can therefore be fed directly fromthe vacuum generator into the supply channel of the sucker. As a result,the supply channel can be reduced to a piece which is only very short.To this end, the respective vacuum generator is arranged on or in thecarrier in such a way that it is as closely as possible to the sucker.

The or each vacuum generator is preferably configured as at least onevacuum pump. The vacuum pump is expediently one which operates accordingto the ejector principle. If a great vacuum or a large volume of airunder negative pressure is required, it is appropriate to use a vacuumpump which operates according to the multiple-stage ejector principle.However, the invention can also be realized with other vacuumgenerators, in particular vacuum pumps which do not operate according tothe ejector principle, but with moving parts, such as paddle wheels.

In particular, a vacuum pump which operates according to the ejectorprinciple or the multiple-stage ejector principle is particularlycompact and can therefore be arranged, according to one preferredrefinement of the invention, in a receptacle in the carrier, whichreceptacle is configured as a simple blind hole or through hole. As aresult, it is possible to accommodate the vacuum pump in the carrier ina particularly space-saving manner and the vacuum pump can be placed asclosely as possible to the sucker in this way, above all, as a result ofwhich only a short supply line having a low volume is required, with theresult that only a small amount of air is to be evacuated out of thesupply line in order to generate a vacuum at the sucker and,accordingly, only a relatively small amount of compressed air has to beused in order to generate the vacuum which is required for attracting bysuction a part of a signature to be separated.

According to one preferred development of the invention, there isprovision for it to be possible also to load the respective sucker withcompressed air from time to time, in particular for a short period. As aresult, rinsing and, in the process, cleaning of the supply channel, butalso of the sucker, takes place. At the same time, the signature isseparated from the sucker, which can be required if the surface of thesignature still has slightly adhesive properties. Paper dust and/orrelease agent can also be eliminated by the cleaning of the sucker,before they can block the sucker or the supply channel which leads to itin an operational interruption.

The supply line can be fed for a short period with compressed air inorder to load the sucker with compressed air. Here, it can be compressedair which passes into the carrier via the connection for feeding thevacuum pump with compressed air. There is then a valve in the carrier,which valve guides the compressed air alternately to the vacuum pump ordirectly to the supply channel of the sucker and, accordingly, eitherfeeds the supply channel with compressed air directly or feeds thevacuum pump in order to generate a vacuum in the supply channel.However, it is also conceivable as an alternative to provide the carrierwith a second connection for compressed air. One of the twocompressed-air connections of the carrier can then optionally besupplied with compressed air by an external, separate controller orvalves, to be precise firstly for feeding the vacuum pump and secondlyfor rinsing the sucker with compressed air.

The invention is also distinguished by a special method for achievingthe abovementioned object. According to this method, there is provisionfor generating the vacuum for supplying the sucker from compressed air.As a result, a separate vacuum supply for the or each sucker issuperfluous. One compressed-air supply is sufficient alone, thecompressed air being converted according to the invention into a vacuum,with which the sucker can be fed.

One development of the method provides for a vacuum flow from compressedair to be accommodated within the tilting sucker, namely a carrier forthe respective sucker which serves as a housing. In this way, the vacuumcan be generated in the immediate vicinity of the sucker, as a result ofwhich only an extremely short supply channel is required for loading thesucker with vacuum, which supply channel can be evacuated quickly onaccount of its shortness, as a result of which the vacuum consumptioncan be reduced considerably by the method according to the invention, incomparison with known tilting suckers.

Furthermore, there is provision, in terms of the method, for the suckerto be supplied briefly with compressed air after a corner or an edgeregion of the respective signature has been tilted away from the stack.Here, separation from the sucker of the signature to be separated isassisted and, at the same time, the sucker including the supply channelis cleaned. Contamination of the sucker and the supply line which leadsto it with, in particular, adhesive residues is therefore avoided in asimple manner. As a result of the brief loading of the sucker withcompressed air, which takes place periodically after each separatingprocess, the tilting sucker does not need to have a filter, in contrastto known tilting suckers.

BRIEF DESCRIPTION OF THE DRAWINGS

One preferred exemplary embodiment of the invention will be described ingreater detail in the following text using the drawing, in which:

FIG. 1 shows a diagrammatic view of a part of a device for print furtherprocessing, namely a collating machine, having the apparatus accordingto the invention, and

FIG. 2 shows a central section through the apparatus according to theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention relates to the field of print further processing. Here,these are devices such as collating machines, adhesive binders or coverfeeders. FIG. 1 shows a part of a collating machine 10 in simplifiedform, namely only one feed station 11 of the collating machine 10 isshown. The feed station 11 has a magazine 12 for accommodating a stack13 of signatures which lie one above the other, which are folded sheets14 in the present case. The folded sheets 14 of the stack 13 areseparated in the region of the feed station 11, by a lowermost foldedsheet 14 being pulled off from under the magazine 12 gradually.

The respectively lowermost folded sheet 14 of the stack 13 is separatedin a first step by the apparatus according to the invention which isconfigured as a tilting sucker 15 in the collating machine 10 which isshown here. An edge region 16 (it also being possible for it to be onlya corner region) of the lowermost folded sheet 14 is tilted away fromthe stack 13 by the tilting sucker 15 (FIG. 2). For this purpose, thetilting sucker 15 shown here has a single sucker 17 which can be loadedwith vacuum and, as a result, can attract by suction the folded sheet 14to be separated from the lower side of the folded sheet 14. The sucker17 is fastened to a carrier 18 of the tilting sucker 15. This carrier 18can be pivoted about a horizontal pivoting axis (not shown in FIG. 1),as a result of which the sucker 17 can be pivoted for attracting bysuction the folded sheet 14 under its edge region 16, and that edgeregion 16 of the lowermost folded sheet 14 which is attracted by suctionby the sucker 17 can be tilted away from the stack 13 of the foldedsheets 14 which lie on top by a subsequent pivoting back.

In the edge region 16 which is tilted away by the tilting sucker 15, thefolded sheet 14 is gripped by grippers (not shown) of a haul-off roll 19and, as a result, the separated folded sheet 14 is transported away fromthe stack 13 to a collecting channel 20 which is shown in basic form inFIG. 1.

The carrier 18 which is shown in FIG. 2 is provided with a protrudingretaining head 22 on a holding face 21 which is oblique in the presentexemplary embodiment. The sucker 17 which is formed from an elasticallyshapeable material, for example an elastomer, a rubber or the like, isconnected to the retaining head 22 by shrinking and/or latching. Here, acircumferential constriction 23 of the retaining head 22 is engagedaround by a rear casing part 24 of the elastic sucker 17.

A supply channel for the sucker 17 is arranged in the interior of thecarrier 18. In the exemplary embodiment shown, this is a supply hole 25in the carrier 18, which supply hole 25 opens with an end region 26 intothe retaining head 22 of the carrier, with the result that the supplyhole 25 is open on the end side of the retaining head 22. The sucker 17has a through hole 27 which corresponds with the end region 26 of thesupply hole 25 in the retaining head 22 and opens into a suction face 28of the sucker 17, which suction face 28 is shaped like a spherical capand is set back concavely with respect to the retaining head 22 (FIG.2).

In a particular manner according to the invention, vacuum for the sucker17 is formed from compressed air, by a vacuum generator which can besupplied with compressed air producing the negative pressure or thevacuum which is required for the sucker 17. In the apparatus accordingto the invention, namely in the exemplary embodiment shown, this vacuumgenerator is assigned to the tilting sucker 15 and the carrier 18.

In the present case, the vacuum generator is a vacuum pump. The latteroperates according to the principle of an ejector which, when compressedair which flows through nozzles flows through axially, generates suctionat the openings of the nozzles, as a result of which the jet ofcompressed air which flows through the nozzles attracts air by suctionand, as a result, generates a vacuum. Both a single-stage ejector and amultiple-stage ejector are suitable as vacuum pump, depending on howgreat the vacuum requirement of the respective tilting sucker 15 is. Inthe case where the tilting sucker 15 should have a plurality of suckers17, which is completely conceivable, a vacuum pump which is formed froma multiple-stage ejector is preferably used.

The vacuum pump 29 shown here has a substantially cylindrical design.The cylindrical vacuum pump 29 is mounted in the carrier 18 of thetilting sucker 15 and is therefore integrated into the tilting sucker15. Here, the carrier 18 forms a housing which surrounds the vacuum pump29. As a consequence of the cylindrical design of the vacuum pump 29, itis situated in a hole 30 in the carrier 18. The hole 30 is configured asa multiple-step through hole. The hole 30 has a threaded hole 32 whichemanates from an end face 31 of the carrier 18, for screwing in a fixedor releasable connection of a compressed-air line (not shown). From thisconnection in the threaded hole 32, the compressed air flows through acentral intermediate section of the hole 30 into an input side 33 of thevacuum pump 29. After the compressed air has flowed through the vacuumpump 29 in the longitudinal direction, the compressed air passes to theoutside via the output end 34 of the vacuum pump 29 which opens into anouter side of the carrier 18, and is mixed there with the surroundingair.

The vacuum which is generated by the vacuum pump 29 passes from thevacuum pump 29 into a transversely oriented connecting hole 35 betweenthe hole 30 for accommodating the vacuum pump 29 and the supply hole 25.The vacuum which is generated by the vacuum pump 29 is guided via acorresponding opening (not shown) in the circumferential face of thevacuum pump 29 via the transversely oriented connecting hole 35 into thesupply hole 25 which extends parallel to the vacuum pump 29, and fromthere to the sucker 17.

The tilting sucker 15 shown here has a second threaded hole 36 in theend face 31, which second threaded hole 36 is situated next to thethreaded hole 32 for supplying the vacuum pump 29 with compressed air.The threaded hole 36 is also provided with a releasable or fixedconnection for a compressed-air line (not shown). The supply hole 25opens into the threaded hole 36. In this way, compressed air can passvia the supply hole 25 directly to the sucker 17. This compressed airserves, after the end of a separation process, to clean the sucker 17,in particular its through hole 27, that is to say (in other words) topurge it with compressed air. For this purpose, compressed air is fed tothe supply hole 25 briefly via the compressed-air connection which isassigned to the threaded hole 36. After cleaning, this compressed-airsupply is closed again, with the result that no more compressed air canpass to the supply hole 25 through the connection of the threaded hole36. A corresponding valve ensures that no air can pass into thecompressed-air line through the compressed-air connection which isassigned to the threaded hole 36 via that end of the supply hole 25which points towards this connection, nor can any air flow from thecompressed-air line into the supply hole 25. In this way, a vacuum canbe built up in the supply hole 25 and the connecting hole 35 despite thesecond connection for compressed air which serves to clean the sucker17.

It can be seen in FIG. 2 that the supply hole 25 is assigned to such alocation of the carrier 18 that it is situated as closely as possible tothe sucker 17 and, as a result, the supply hole 25 and also theconnecting hole 35 are kept as short as possible. Accordingly, only acomparatively low volume has to be sucked away during the build-up ofthe vacuum at the sucker 17, until a vacuum is set in the supply hole 25and air for attracting by suction a folded sheet 14 or another signature(vacuum) is produced through the through hole 27 in the centre of thesuction face 28 of the sucker 17.

The method on which the invention is based will be explained in greaterdetail in the following text:

The special feature of the invention consists in that, in an apparatusfor tilting away a part of a signature to be separated, the tiltingsucker 15 in the exemplary embodiment shown, the vacuum which isrequired for the sucker 17 is generated from compressed air. Thecompressed air is converted into vacuum in the immediate vicinity of thesucker 17 by at least one vacuum generator, the vacuum pump 29 in theexemplary embodiment shown. The vacuum pump 29 is assigned directly tothe tilting sucker 15, and it is namely situated on or in the tiltingsucker 15. The vacuum pump 29 is supplied with compressed air. When thecompressed air flows through the vacuum pump 29, the latter generates avacuum according to the ejector principle, which vacuum is guidedthrough the interior of the carrier 18 to the sucker 17. The generatedvacuum at the sucker 17 can be varied by changing the amount ofcompressed air which is fed to the vacuum pump 29 and/or the pressure ofthe said compressed air.

When the sucker 17 is moved towards the edge region 16 to be tilted awayof the lowermost folded sheet 14, which movement takes place by pivotingof the tilting sucker 15, the compressed-air supply of the vacuum pump29 is started. On account of the immediate vicinity of the vacuum pump29 with respect to the sucker 17, only the relatively short supply hole25 (also the connecting hole 35 in the exemplary embodiment shown) hasto be evacuated, until vacuum is present at the central through hole 37of the suction face 28 of the sucker 17. This is the case, as soon asthe suction face 28 of the sucker 17 is in contact below the edge region16 of the folded sheet 14. As a result, the lower edge of the edgeregion 16 is attracted by suction and, when the carrier 18 pivots backfrom the sucker 17, the edge region 16 of the lowermost folded sheet 14is tilted away from the stack 13 which lies above it.

The vacuum supply of the sucker 17 is cancelled by interruption of thecompressed-air supply to the vacuum pump 29 in temporal coordinationwith the gripping of the tilted-away edge region 16 of the folded sheet14 by the haul-off roll 19. As a rule, the edge region 16 of the foldedsheet 14 is released automatically as a result from the sucker 17, withthe result that the folded sheet 14 can be transported further by thehaul-off roll 19.

According to one preferred development of the method, the tilting sucker15 shown is provided with a second connection for compressed air. Thisconnection is assigned to the threaded hole 36 of the carrier 18. Thesucker 17 can be cleaned with compressed air through the secondcompressed-air connection, the release of the tilted-away edge region 16of the folded sheet 14 from the suction face 28 of the sucker 17 alsobeing assisted.

The above-described purging of the sucker 17 by compressed air takesplace after the edge region 16 of the folded sheet 14 has previouslybeen attracted with vacuum by the sucker 17 and has been tilted away. Inorder to clean the sucker 17, the two compressed-air supplies of thecarrier 18 are switched over. The compressed air which is requiredinitially for supplying the vacuum pump 29 is fed to the carrier 18through the first compressed-air connection (the threaded hole 32).After the edge region 16 has been tilted away, the said firstcompressed-air supply is closed and, instead, the sucker 17 is suppliedbriefly with compressed air via the second compressed-air connection(threaded hole 36) through the carrier 18, as a result of which thesucker 17, in particular the through hole 27 in its suction face 28, iscleaned pneumatically. In other words, the sucker 17 is cleanedaccording to the invention by purging with air. As soon as the cleaningprocess of the sucker 17 is ended, which only requires a few seconds,the second compressed-air supply (threaded hole 36) is also interrupted.

As soon as the next working cycle begins, that is to say an edge region16 of a folded sheet 14 to be separated next is to be tilted away by thetilting sucker 15 in order to separate the next folded sheet 14 from thestack 13, the compressed-air supply of the first compressed-airconnection (threaded hole 32) is opened again shortly before theunderside of the edge region 16 is attracted by suction and, as aresult, the vacuum pump 29 is again supplied with compressed air for acertain time, which compressed air is converted by the vacuum pump 29into vacuum for supplying the sucker 17.

The invention is suitable not only for collating machines 10, but alsofor other machines for print further processing. While the tiltingsucker 16 shown has one sucker 17 and one vacuum pump 29, it isconceivable to assign a plurality of suckers 17 to a tilting sucker forother cases of use, in particular for other machines for print furtherprocessing. The carrier of the tilting sucker can then also have aplurality of vacuum generators, in particular vacuum pumps 29. It isalso conceivable to supply a vacuum to a plurality of suckers 17 at thesame time from one vacuum pump. The vacuum pump 29 is then expedientlyconfigured as a multiple-stage ejector pump.

LIST OF REFERENCE NUMERALS

-   10 Collating machine-   11 Feed station-   12 Magazine-   13 Stack-   14 Folded sheet-   15 Tilting sucker-   16 Edge region-   17 Sucker-   18 Carrier-   19 Haul-off roll-   20 Collecting channel-   21 Holding face-   22 Retaining head-   23 Constriction-   24 Casing part-   25 Supply hole-   26 End region-   27 Through hole-   28 Suction face-   29 Vacuum pump-   30 Hole-   31 End face-   32 Threaded hole-   33 Input side-   34 Output side-   35 Connecting hole-   36 Threaded hole

1. Apparatus for tilting away a part of a signature to be separated froma stack (13), having at least one sucker (17) which is arranged on acarrier (18) and can be moved, preferably pivoted, by the carrier (18)for tilting away a part of the signature to be separated, and having atleast one supply channel in the carrier (18) for supplying therespective sucker (17) with vacuum, characterized in that the carrier(18) is assigned at least one vacuum generator for providing the vacuumwhich is required by the respective sucker (17).
 2. Apparatus accordingto claim 1, characterized in that the vacuum generator is configured forgenerating a vacuum from compressed air.
 3. Apparatus according to claim1, characterized in that the vacuum generator is assigned to the sucker(17).
 4. Apparatus according to claim 3, characterized in that thevacuum generator is arranged in the vicinity of the sucker (17). 5.Apparatus according to claim 1, characterized in that the vacuumgenerator is arranged in the carrier (18).
 6. Apparatus according toclaim 1, characterized in that the carrier (18) has at least onecompressed-air connection for supplying the at least one vacuumgenerator with compressed air.
 7. Apparatus according to claim 1,characterized in that the amount of compressed air which can be fed tothe at least one vacuum generator can be changed.
 8. Apparatus accordingto claim 7, characterized in that the amount of compressed air which canbe fed to the at least one vacuum generator can be changed by aplurality of valves which are to be actuated individually.
 9. Apparatusaccording to claim 1, characterized in that the pressure of thecompressed air which can be fed to the at least one vacuum generator canbe changed.
 10. Apparatus according to claim 1, characterized in thatthe supply channel of the at least one sucker (17) can be fed withvacuum which is formed by the vacuum generator.
 11. Apparatus accordingto claim 1, characterized in that the supply channel for the at leastone sucker (17) has as low a volume as possible.
 12. Apparatus accordingto claim 1, characterized in that the supply channel for the at leastone sucker (17) has as small a length as possible as a result of thevacuum generator being arranged as closely as possible to the sucker(17).
 13. Apparatus according to claim 1, characterized in that therespective vacuum generator is configured as at least one vacuum pump(29).
 14. Apparatus according to claim 13, characterized in that thevacuum pump (29) is arranged in a receptacle in the carrier (18). 15.Apparatus according to claim 14, characterized in that the receptaclefor the vacuum pump (29) in the carrier (18) is configured as at leastone hole (36).
 16. Apparatus according to claim 13, characterized inthat the vacuum pump (29) is configured as a vacuum pump (29) whichoperates according to the ejector principle.
 17. Apparatus according toclaim 1, characterized in that the respective sucker (17) can be loadedwith compressed air for a short period in order to tilt a signatureaway.
 18. Apparatus according to claim 17, characterized in that, inorder to load the respective sucker (17) with compressed air, the supplychannel of the sucker (17) can be fed with compressed air for a shortperiod.
 19. Apparatus according to claim 14, characterized in that thecarrier (18) has an additional connection for compressed air, whichadditional connection opens into the supply channel for the respectivesucker (17) and can be closed if required.